As it happens I flew on Saturday through a small cloud that happened to be in the way (yes I know, naughty). I could see right through it as I approached it, and had the sun behind me.
As I flew into it, for the 5 seconds or so it took me to pass through I had this amazing sight of a profile of my aeroplane right in front of me surrounded by a huge white halo. Rather spooky - particularly since I couldn't see anything else for the duration.
I've read somewhere about a similar phenomenon being seen by hillwalkers in cloud, although I've been flying and hillwalking for years, it's the first time I've seen anything quite so striking.
G